Focal plane shutter and mechanism for operating

ABSTRACT

A focal plane shutter includes a pair of curtains formed of a one-piece member of readily flexible material having corrugations running in a direction perpendicular to the direction of curtain travel. The curtains are guided in opposed grooved of width substantially equal to the depth of the corrugations. The curtains ride in the grooves on a pair of pins and are driven by a pair of spring-biased transmission plates which are cocked by a tensioning lever and are latched in their cocked positions by a pair of armature levers. One of the armature levers is released by the tensioning lever while the other armature lever is released by a timing device after a delay period.

United States atom Ort et al.

1 Feb. 29,1972

[54] FOCAL PLANE SHUTTER AND MECHANISM FOR OPERATING [72] inventors: Wolfgang Ort; Gerhard Brauning, both of Stuttgart-bad Connstatt, Germany 211 Appl. No.: 809,590

[30] Foreign Application Priority Data May 14, 1969 Germany ..P I7 72 427.5

[52] US. Cl ..95/55, 95/57 [51] Int. Cl. ..G03b 9/36 [58] Field 0fSearch..... ..95/55,57

[56] References Cited UNITED STATES PATENTS 2,901,954 9/1959 Amano ..95/55 3,082,673 3/1963 Takahama ..95/55 3,138,083 6/1964 Thomas et a1. ...95/57 3,511,158 5/1970 Nerwin ..95/57 FOREIGN PATENTS OR APPLICATIONS 880,908 10/1961 Great Britain ..95/55 Primary Examiner-John M. Horan Assistant Examiner-Michael D. Harris AttorneyRobert W. Hampton and Milton S. Sales [57] ABSTRACT A focal plane shutter includes a pair of curtains formed of a one-piece member of readily flexible material having corrugations running in a direction perpendicular to the direction of curtain travel. The curtains are guided in opposed grooved of width substantially equal to the depth of the corrugations. The curtains ride in the grooves on a pair of pins and are driven by a pair of spring-biased transmission plates which are cocked by a tensioning lever and are latched in their cocked positions by a pair of armature levers. One of the annature levers is released by the tensioning lever while the other armature lever is released by a timing device after a delay period.

8 Claims, 3 Drawing Figures PATENTEDFEBZS m2 3. 646, 603

sum 1 OF 3 26 a 1 A 9T 42 a 30 J Fle. 2

42 WOLFGANG ORT 4O GERHARD BRAUNING INVENTORS H BY 22 I J M ATTORNEYS PATENTEDFEB29 I972 SHEEI 3 [1F 3 WOLFGANG o RT GERHARD BRAUNING INVENTORS CROSS-REFERENCE TO RELATED APPLICATION Reference is made to commonly assigned copending U.S. Patent Application Ser. No. 800,310, entitled Focal Plane Shutter, filed in the name of Hubert Nerwin on Dec. 23, 1968 now U.S. Pat. No. 3,511,158.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a focal plane shutter for cameras and to a mechanism for operating the shutter.

2. Description of the Prior Art Focal plane shutters adapted to ride in guide grooves during unidirectional running-down movement have been previously adapted for cameras manufactured to receive size 126 film cartridges. One such example of a focal plane shutter for a size 126 camera is described in U.S. Pat. No. 3,511,158. As pointed out in that patent application, the use of a focal plane shutter in a cartridge camera is made difficult due to the requirements of drive-pulley size and location and because of the additional light-sealing means necessary to protect the film cartridge. The invention disclosed in the above-noted patent application solves the problem by employing driving rollers having specially geared wheels which drive the curtains on two opposite sides of the exposure area. In that case, the curtains consist of many individual members provided with a head portion for engagement with the driving gears. The number of individual members permits the curtains to run smoothly along the guide grooves.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a focal plane shutter suitable for use in l26-size cameras having sim- Y plified manufacture and assembly.

It is another object of the present invention to provide a simplified drive mechanism for focal plane shutters.

In accordance with a preferred embodiment of the present invention, a focal plane shutter consists of at least one curtain comprising a single piece of flexible sheet material having rigidity in a direction perpendicular to the direction of travel. The flexible sheet which comprises the curtain is preferably manufactured as an integral unit of spring sheet steel which, owing to its thinness, is flexible so as to easily traverse a curved path of travel. To achieve stiffness in the direction transverse to the direction of travel, the curtains are provided with corrugations extending perpendicularly to the direction of movement.

Normally, two such curtains are provided and are preferably driven from only one side, i.e., by a mechanism which is arranged either above or below the film gate, so that the other side may be used for other camera elements such as a viewfinder, a film advance cocking mechanism or an exposure meter. The curtains are driven by means of an L-shaped lever which is pivotally mounted to the camera base. The levers are rotatably supported in the center of the circular por tion of the guide groove, thus saving the space which would normally be required for additional driving shafts and gears.

A preferred drive mechanism for the levers consists of a transfer plate associated with each lever and rotatably mounted to the camera base. The plates are spring-biased towards the curtain run-down position and are cocked against the bias of the spring by a tensioning lever which is pivotally mounted between the transfer plates. A pair of armature levers latch the transfer plates in their cocked positions and the transfer plate associated with the leading curtain is released upon movement of the tensioning lever after the shutter release has been depressed. A time delay mechanism releases the transfer plate associated with the trailing curtain after a predetermined period calculated for proper exposure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmental, perspective view of a camera and film cartridge showing the arrangement of the focal plane shutter of the present invention;

FIG. 2 is top and elevational views of the shutter curtain in FIG. I;

FIG. 3 is a fragmental, sectional view of the shutter mechanism when both curtains are cocked taken through line 3-3 of FIG. 1;

FIG. 4 is a bottom plan view taken along line 44 of FIG. 3 showing the shutter mechanism in cocked condition; and

FIG. 5 is a bottom plan view of the shutter mechanism at the moment when the leading curtain has passed the film gate and before the trailing curtain has been released.

DESCRIPTION OF THE PREFERRED EMBODIMENT Because cameras are well known, the present description will be directed in particular to elements forming part of, or cooperating more directly with apparatus in accordance with the present invention. It is to be understood that camera elements not specifically shown or described may take various forms well known to those skilled in the art.

Referring to FIG. 1, a camera 10 has upper and lower walls 12 and 14 with guide grooves 16 and 18, respectively, said guide grooves corresponding approximately to the cross-sectional shape of a film cartridge 20 of known construction. A pair of curtains 22 and 24 are positioned to move in grooves 16 and 18 in the general direction of arrow C during shutter action and in the opposite direction during shutter cocking. Lead curtain 22 is shown in its rundown position while trailing curtain 24 is shown in its cocked position.

As shown more clearly in FIG. 2, each curtain consists of a thin steel strip which is provided with reinforcing creases or corrugations 26 across the curtain in a direction transverse to the direction of curtain movement. Creases 26 are provided to impart lateral strength to the curtains and to improve the curtain-sliding properties in grooves 16 and 18 by reducing the contact area between the curtains and the lateral walls of the grooves. The ends of each curtain are provided with guide pins 28 and 30 which project beyond the top and bottom edges of the curtains, by an amount a to produce only point contact with the bottom of grooves 16 and 18. Guide pins 28 and 30 are mounted on the curtain sheet in such a manner that the curtain sheet nearly completely encloses the pin, vertical displacement between the curtain and pins being prevented by embossments 32.

Lead curtain 22 is drawn by means of a lever 34 during shutter action. In the course of this process, an edge 36 of lever 34 acts upon an edge 38 of a cutout 40 in curtain 22. Edge 38 is spaced from guide pin 28 by a small amount b. When the curtain is running down, edge 38 is elastically deformed by the driving force of lever 34 to such as extent that edge 36 of lever 34 acts on guide pin 28 as well as on edge 38. Thus, the driving force is distributed between curtain sheet 22 and guide pin 28, preventing permanent deformation of either the pin or the curtain. Contact between lever 34 and the curtain is near the transverse center of the curtain to prevent cocking the curtain in grooves 16 and 18. This eliminates the possibility of curtain jamming.

For insuring that curtains 22 and 24 form a lighttight closure as they are drawn to the right as seen in FIG. 1, curtain 22 is provided with a lip 42 which is formed by slitting the curtain in two places and not folding the lip portion over pin 30.

The shutter-driving mechanism is shown in FIGS. 3-5. FIG. 3 is a sectional view taken towards the rear of the camera. A lever 43 is positively connected to driving shaft 44 which is in turn rotatably seated in a sleeve 46. A bore-and-counter bore 48 in base or lower wall 14 accommodates a driving spring 50 for curtain 24. One leg of driving spring 50 is held in a groove, not shown, of lower wall 14 by one of its legs, while the other leg rests against a bent portion 54 of a spring-holding plate 56.

Spring-holding plate 56 is rotatably seated on driving shaft 44. A transmission plate 58 is seated below spring holding plate 56 and positively connected with driving shaft 44 by means of a screw 60. Spring holding plate 56 is firmly connected to transmission plate 58 by a screw 62. When screw 62 is loosened, the driving force of spring 50 can be adjusted within a relatively large range by turning spring holding plate 56 with respect to transmission plate 58. For this purpose, an arcuate recess 64 (FIGS. 4 and is provided in transmission plate 58. A guide pin 66 is riveted to transmission plate 58.

As appears from FIG. 3, the driving mechanism thus far set forth is the same for both curtains, like elements being designated with prime marks when referring to the structure associated with lead curtain 22. Guide pins 66 and 66' of transmission plates 58 and 58' rest against edges 68 and 68 (FIG. 4) of a tensioning lever 70 which is pivotally mounted on a screw 72 and a spacer sleeve 74. A cocking lever 76 having a cocking key 78 is also pivotally mounted on screw 72. Between tensioning lever 70 and cocking lever 76, a restoring spring 80 is arranged about sleeve 74. One leg of restoring spring 80 rests against a setscrew 82 and the other leg against bent portion 84 of tensioning lever 70. A second restoring spring 86 for cocking lever 76 is wound about screw 72. One leg of restoring spring 86 rests against a bent portion 88 of cocking lever 76, the other leg against screw 82 and, simultaneously, against a point 90 of an armature lever 92 for transmission plate 58 associated with curtain 24. Thus, the need for a special spring for armature lever 92 is eliminated.

Armature lever 92 is pivotally mounted about a setscrew 94 and, with its angular portion 96, forms a connection to a shutter-timing device. In the embodiment shown, it has been assumed that this timing device is of an electrical or electronical type and comprises an electromagnet 98 for which angular portion 96 or armature lever 92 forms the electromagnet armature.

A release pawl 100 for transmission plate 58', which is associated with lead curtain 22, is pivotally supported on a bearing bolt 102 and is biased in a counterclockwise direction as shown in FIG. 4 by a spring 104. A release lever 106 is guided in a slot 108 in lower wall 14 and held by a setscrew 110. After being released, release lever 106 is restored to its initial position by a leaf spring 112. A pair ofscrews 114 and 116 serve as stops for cocking lever 76 and tensioning lever 70, respectively (see FIG. 5).

OPERATION When cocking key 78 is depressed to cock the shutter mechanism, tensioning lever 70 is rotated in counterclockwise direction by means of cocking lever 76, via an abutment 118. Thus, transmission plates 58 and 58 are turned in counterclockwise directions via abutment edges between 68 and 68 of tensioning lever 70 and guide pins 66 and 66. Transmission plates 58 and 58' are effective in turn to move curtains 24 and 22 by way oflevers 43 and 34.

Release lever 106 has a bevelled surface 120, the edge 122 of which cooperates with an edge 123 oftensioning lever 70 to lock-tensioning lever 70 in the cocked position shown in FIG. 4. When cocking lever 76 is released, spring 86 urges it toward its initial position shown in FIG. 5 until it reaches the stop screw 114. Transmission plates 58 and 58 are held by edges 68 and 68 of tensioning lever 70 in such a manner that detents 90 and 124 of armature lever 92 and release pawl 100, respectively, remain ineffective.

When the shutter is to be released for the purpose of effecting an exposure, release lever 106 is depressed in the direction of arrow B (FIG. 3) until edge 122 of bevelled portion 120 releases edge 123 of tensioning lever 70. Under the bias of spring 80, tensioning lever 70 pivots about screw 72 in the direction of arrow A. In the course of this process, a switching member 126, which is shown here as a change-over switch, is reversed via an edge 128 of tensioning lever 70 so that the electronic system assumed to be incorporated in the embodiment may start to integrate in a known manner. During this period, transmission plates 58 and 58' are held by armature lever 92 and release pawl 100, respectively. In the further courseof travel of tensioning lever 70, and edge 130 strikes against a bent portion 132 of release pawl I00, disengaging the pawl from detent 124 on transmission plate 58'. The pivotal movement of tensioning lever 70 is arrested when it strikes against stop screw 116, edges 68 and 68' now serving as stops for pins 66 and 66' on transmission plates 58 and 58,

respectively. Transmission plate 58', and thus, curtain 22 is turned by the force of driving spring 50' until pin 66' abuts against edge 68 of tensioning lever 70.

Now the shutter is in its open position, as shown in FIG. 5. Catch of armature lever 92 prevents a premature release of transmission plate 58. This release can safely be effected only after a predetermined time delay. This time delay can be effected either mechanically or, as shown, electronically by exciting electromagnet 98 by capacitor discharge. In the course of this process, angular portion 96 of armature lever 92 is attracted by electromagnet 98 to release transmission plate 58. Transmission plate 58 turns under the influence of spring 50 until guide pin 66 strikes against edge 68 of tensioning lever 70. By this time, curtain 24 has reached its final position, and the exposure process is terminated.

The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

1. A mechanism for driving a lead and a trailing focal plane shutter in a camera between cocked and rundown positions, said mechanism comprising:

a. resilient means biasing the shutters toward their rundown positions;

b. first and second latch means associated with the lead and trailing shutters, respectively, to releasably hold the shutters in their cocked positions;

. tensioning lever means movable to a first position for moving the shutters against the bias of said resilient means to' their cocked positions and to a second position for releasing only said first latch means, the first shutter moving to its rundown position in response to the movement of said lever means from the first position to the second position while the secondshutter remains in its cocked position;

d. first and second transmission plates rigidly attached to said lead and trailing shutters, respectively;

e. first and second abutments on said first and second transmission plates, respectively; and

f. first and second surfaces on said lever means for cooperating with said first and second abutments, respectively, to move the shutters to their cocked positions upon movement of said lever means to its first position.

2. A focal plane shutter apparatus for a camera having an exposure area with opposite lateral ends, and a film-receiving chamber adjacent each the lateral ends, said apparatus comprising:

at least one shutter curtain movable in a path across the exposure area, said curtain comprising an integral sheet of readily flexible material having upper and lower edge portions and corrugations extending in a direction perpendicular to said edge portions;

means for guiding said shutter curtain through a path having a middle portion in front of the exposure area and opposite end portions curved about the receiving chambers, said guiding means comprising opposed grooves extending substantially along said path for receiving the opposite edge portions of said shutter curtain.

3. A focal plane shutter apparatus as defined in claim 2 wherein:

the depth of said corrugations is substantially equal to the width of said guide grooves.

4. A focal plane shutter apparatus as defined in claim 2 wherein:

said shutter curtain comprises guide pins extending beyond the edge portions of said curtain, whereby frictional contact between said edge portions and the bottom of said grooves is limited to the contact area between said guide pins and the bottom of said grooves. 5. A focal plane shutter apparatus as defined in claim 2 wherein:

the depth of said corrugation is substantially equal to the width of said guide grooves. 6. A focal plane shutter apparatus as defined in claim 2 further comprising curtain-driving means including a lever pivotally mounted in and substantially coaxial with a camerafilm-receiving chamber, said lever being in driving contact with said curtain at approximately the center of said curtain taken in a direction perpendicular to the direction of curtain movement along said guide path.

7. A mechanism for operating a focal plane shutter, said mechanism comprising:

a. a base;

b. first and second shutter curtains;

c. first and second transmission plates attached to said first and second curtains, respectively, said plates being rotatably mounted in said base for movement between curtain cocked and curtain rundown positions;

d. means biasing said transmission plates towards their rundown positions;

e. first and second latches for holding said first and second transmission plates, respectively, in their cocked positions; and

f. a tensioning lever pivotally mounted on said base and having means for moving said transmission plates to their cocked positions when rotated in one direction and means for releasing said first latch when rotated in the opposite direction.

8. A mechanism as defined in claim 7 further comprising:

a. resilient means biasing said tensioning lever in said opposite direction;

b. a third latch for holding said tensioning lever against the force of said resilient means; and

c. a release lever for releasing said third latch. 

1. A mechanism for driving a lead and a trailing focal plane shutter in a camera between cocked and rundown positions, said mechanism comprising: a. resilient means biasing the shutters toward their rundown positions; b. first and second latch means associated with the lead and trailing shutters, respectively, to releasably hold the shutters in their cocked positions; c. tensioning lever means movable to a first position for moving the shutters against the bias of said resilient means to their cocked positions and to a second position for releasing only said first latch means, the first shutter moving to its rundown position in response to the movement of said lever means from the first position to the second position while the second shutter remains in its cocked position; d. first and second transmission plates rigidly attached to said lead and trailing shutters, respectively; e. first and second abutments on said first and second transmission plates, respectively; and f. first and second surfaces on said lever means for cooperating with said first and second abutments, respectively, to move the shutters to their cocked positions upon movement of said lever means to its first position.
 2. A focal plane shutter apparatus for a camera having an exposure area with opposite lateral ends, and a film-receiving chamber adjacent each the lateral ends, said apparatus comprising: at least one shutter curtain movable in a path across the exposure area, said curtain comprising an integral sheet of readily flexible material having upper and lower edge portions and corrugations extending in a direction perpendicular to said edge portions; means for guiding said shutter curtain through a path having a middle portion in front of the exposure area and opposite end portions curved about the receiving chambers, said guiding means comprising opposed grooves extending substantially along said path for receiving the opposite edge portions of said shutter curtain.
 3. A focal plane shutter apparatus as defined in claim 2 wherein: the depth of said corrugations is substantially equal to the width of said guide grooves.
 4. A focal plane shutter apparatus as defined in claim 2 wherein: said shutter curtain comprises guide pins extending beyond the edge portions of said curtain, whereby frictional contact between said edge portions and the bottom of said grooves is limited to the contact area between said guide pins and the bottom of said grooves.
 5. A focal plane shutter apparatus as defined in claim 2 wherein: the depth of said corrugation is substantially equal to the width of said guide grooves.
 6. A focal plane shutter apparatus as defined in claim 2 further comprising curtain-driving means including a lever pivotally mounted in and substantially coaxial with a camera-film-receiving chamber, said lever being in driving contact with said curtain at approximately the center of said curtain taken in a direction perpendicular to the direction of curtain movement along said guide path.
 7. A mechanism for operating a focal plane shutter, said mechanism comprising: a. a base; b. first and second shutter curtains; c. first and second transmission plates attached to said first and second curtains, respectively, said plates being rotatably mounted in said base for movement between curtain cocked and curtain rundown positions; d. means biasing said transmission plates towards their run-down positions; e. first and second latches for holding said first and second transmission plates, respectively, in their cocked positions; and f. a tensioning lever pivotally mounted on said base and having means for moving said transmission plates to their cocked positions when rotated in one direction and means for releasing said first latch when rotated in the opposite direction.
 8. A mechanism as defined in claim 7 further comprising: a. resilient means biasing said tensioning lever in said opposite direction; b. a third latch for holding said tensioning lever against the force of said resilient means; and c. a release lever for releasing said third latch. 